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Chapter 4: JOINs
Try It Out FULL JOINs
102
Let’s just get right to it by looking back at our previous query from the section on OUTER JOINs:
SELECT v.VendorName, a.Address
FROM VendorAddress va
JOIN Address a
ON va.AddressID = a.AddressID
RIGHT OUTER JOIN Vendors v
ON v.VendorID = va.VendorID
What we want to do here is take it a piece at a time again and add some fields to the SELECT list that will
let us see what’s happening. First, we’ll take the first two tables using a FULL JOIN:
SELECT a.Address, va.AddressID
FROM VendorAddress va
FULL JOIN Address a
ON va.AddressID = a.AddressID
As it happens, a FULL JOIN on this section doesn’t yield any more than a RIGHT JOIN would have:
Address AddressID
-------------- -------------
1234 Anywhere 1
567 Main St. 3
999 1st St. NULL
1212 Smith Ave NULL
364 Westin NULL
(5 row(s) affected)
But wait — there’s more! Now add the second JOIN:
SELECT a.Address, va.AddressID, v.VendorID, v.VendorName
FROM VendorAddress va
FULL JOIN Address a
ON va.AddressID = a.AddressID
FULL JOIN Vendors v
ON va.VendorID = v.VendorID
Now we have everything:
Address AddressID VendorID VendorName
-------------- ---------- ---------- -------------------------------
1234 Anywhere 1 1 Don’s Database Design Shop
567 Main St. 3 2 Dave’s Data
999 1st St. NULL NULL NULL
1212 Smith Ave NULL NULL NULL
364 Westin NULL NULL NULL
NULL NULL 3 The SQL Sequel
(6 row(s) affected)